1. The Field of the Invention
The present invention relates to a device and methods for modifying an atmosphere. More specifically, the present invention relates to the use of a mixture of acetylsalicylic acid and sodium bicarbonate to modify an atmosphere.
2. The Prior State of the Art
The preservation of fish has been a major concern for fishermen and fish processors for centuries. Originally, man salted and dried fish to preserve it. Since the advent of mechanical refrigeration, fish have been preserved by freezing and refrigeration, thus permitting fishermen to make longer fishing trips, as well as transport the fish long distances over land or water.
The length of time over which fish maintains its freshness is commonly referred to as its shelf life. The shelf life of fish is determined by a number of factors, including the total number of each type of bacteria initially present, the specific types of bacteria present, the temperature of the flesh of the fish and of the surrounding atmosphere, and the pH of the fish. It is known that to extend the shelf life of fish, one may, for example, reduce the number of bacteria present using chemical means, freezing or other methods, create an acidic pH and/or maintain the product below 5xc2x0 C. in its fresh state. The most common process employed to extend the shelf life of fish is freezing.
An inherent problem with freezing fish is its loss of the xe2x80x9cfreshxe2x80x9d attributes such as a xe2x80x9cpinkxe2x80x9d or xe2x80x9credxe2x80x9d meat color to both the fish flesh and the xe2x80x9cblood linexe2x80x9d in the fish. The loss of these attributes causes the value of the frozen fish to be much less than the value of fish that has not been previously frozen. This loss of value is an interpretation of the quality of the fish by the consumer. The color of the flesh and blood line of the fish is a major factor in the selling of seafood at the consumer level. Most consumers purchase fish with their eyes rather than with any other factor, such as smell, taste or texture. Therefore, it is desirable to maintain the xe2x80x9cfreshxe2x80x9d pink/red color of the seafood products as long as possible in order to sell the product at a premium to consumers.
Although many factors may effect changes to the color of fish products, the main reduction of color results from damage to the hemoglobin pigments in the fish. Several of the primary causes for the reduction of hemoglobin pigments, resulting in a corresponding reduction in the xe2x80x9cfreshxe2x80x9d color of the fish, include oxidation of the xe2x80x9credxe2x80x9d hemoglobin pigments in the flesh to a xe2x80x9cbrownxe2x80x9d color; bacterial decomposition of the cells containing the hemoglobin pigments; and destruction and oxidation of the hemoglobin pigment during freezing.
Most unfrozen fish is considered xe2x80x9cfreshxe2x80x9d for as many as 30 days from catching. However, unfrozen fish this old usually contains high levels of dangerous bacterial decomposition. Bacterial decomposition of fish is the cellular breakdown of the flesh of the fish due to the digestive enzymes of bacteria present on or within the flesh of the fish. Conversely, frozen fish is usually frozen upon catching which reduces the likelihood that the fish will contain significant or harmful levels of bacterial decomposition.
U.S. Pat. No. 6,106,775 discloses a device for modifying an atmosphere in proximity to the device, wherein the device comprises a rigid shell with at least one hole formed therethrough, wherein the shell encases an absorbent material, wherein the absorbant material is adapted to absorb an aqueous composition, and wherein the aqueous composition is formed from combining water, acetylsalicylic acid, and sodium bicarbonate. The atmosphere can be that of a refrigerated space where food (i.e. meat) is stored. In operation, the device is immersed in a volume of water, and placed in a selected atmosphere. Water is evaporated from the absorbant material into the air contained within the shell. Although not explicitly disclosed, carbon dioxide gas is inherently produced by the combination of water, acetylsalicylic acid, and sodium bicarbonate. Thus, in addition to water vapor, carbon dioxide gas is also introduced into the air contained within the shell. The hole or holes in the shell permit the flow of these two gases into the surrounding atmosphere, therey modifying the same. If a food product has been placed in this atmosphere, the now modified atmosphere facilitates a prolonging of the shelf life of the food product. Critical to this invention is the fact that non-vaporous (i.e. liquid) water must be externally applied to the absorbant material, such as by immersing the shell containing the absorbant material in a volume of water, or by pouring water over the shell. Although this device is operable in a variety of environments, the device suffers from the fact that water must be externally and, ultimately, continuously supplied. The device further suffers from the related problem that if the temperature of the atmosphere in which the device is placed is 0xc2x0 C. or lower, the device is inoperable due to freezing of the water.
Given the current state of the art, it would be desirable to obtain a device for modifying an atmosphere in proximity to the device wherein the device does not require the external and continuous application of liquid water and which is operable at below-freezing temperatures. It would be further desirable to obtain methods for modifying an atmosphere that similarly do not require the external and continuous application of liquid water.
In one aspect of the invention, there is provided a device for modifying an atmosphere in proximity to the device, the device comprising a sachet comprising a semipermeable material; and a composition including a mixture of acetylsalicylic acid and sodium bicarbonate contained within a cavity of the sachet.
In another aspect of the invention, there is provided a method for modifying an atmosphere comprising placing a mixture of a carboxylic acid and a base in the atmosphere, wherein the atmosphere has a sufficient level of water vapor such that, upon contact of the water vapor with the mixture, carbon dioxide is produced.
In another aspect of the invention, there is provided a method for modifying an atmosphere comprising placing a sachet in the atmosphere, wherein the sachet contains a mixture of a carboyxlic acid and a base, and wherein the atmosphere has a sufficient level of water vapor such that, upon contact of the water vapor with the mixture, carbon dioxide is produced.